Hi again!
I am not ignoring the fact that three different speed values were reported by the three ADIRU:s. However, we donīt know if one of them was correct. I fully agree with you and others that pitot failure is a probable cause - but not necessarily the only one. I donīt think the ACARS system measures any analogue signals, e.g. the pressures from the ports.
If you read the BEA 2:nd report carefully you will find that not all ACARS events have been fully understood/explained.
Personally I think that temporary hardware or software errors perhaps also may have interfered with some operations of the data busses. There is at least one incident report where one faulty computer locked up a bus thus preventing the other healthy computer access. When I was involved in the design of very large automated multi-computer controlled systems years ago (probably more complex than those on the Airbusses) it was often forbidden for safety reasons to use bus-type signal connections because these were sensitive to single electronic faults anywhere along the bus. However, I understand the need for bus-type connections on an aircraft due to weight limitations etc.